Powering a city is a major undertaking: all that economic activity, culture and innovation requires a lot of fuel. As a result, while cities house just over half the world’s population, but are responsible for nearly 80 per cent of the world’s energy consumption.

The result of all this is rising greenhouse gas emissions. This year looks set to smash all previous temperature records, and cities are no strangers to the consequences of a hotter planet. From rising sea levels, encroaching on coastline properties, to droughts and heatwaves that threaten citizens and businesses, the likes of Bangkok, Paris, New York and countless others know what climate change looks like first hand.

So what can be done about it? Weaning our cities off fossil fuels, the most polluting sources of energy, is key – but this is much more easily said than done. Many city governments lack the ability to directly control the energy mix of their electricity as policies are often set at state or national levels. With few national governments setting ambitious goals to be fossil fuel-free, the odds appear stacked against cities.

Despite these challenges, some major cities are showing that it is possible to reduce fossil fuel usage. This year over 300 cities joined in CDP’s cities programme, sharing information on how they are taking actions to reduce carbon emissions and managing climate risks. Over a third of these cities told us they have some kind of renewable energy goal in place. More promisingly still, some, including the city of Aspen in the US, have in fact already declared themselves fossil fuel-free.

Here are five cities already making the shift to a low-carbon future.

Cape Town, South Africa

Locals in Cape Town, who affectionately refer to it as the Mother City, are familiar with the country’s ongoing issues with energy supply and demand. Over the past six years the price of electricity has jumped by 340 per cent, putting a strain on local businesses and households. The city’s current energy mix is heavily reliant on coal, which supplies up to 72 per cent of its electricity.

However with growing concern over energy security and the city’s high carbon footprint, officials are catalysing a transition to renewables. Cape Town aims to source 10 per cent of the city’s electricity from renewable energy by 2020 – a change that will save greenhouse gas emissions by 1m metric tons.

Houston, Texas

Texas may be known as an oil-rich state, but its most populous city, Houston, happens to be the largest municipal purchaser of green power in the US. The city estimates it is using almost 623,000 mWh of green power per year, which is equivalent to the amount of energy needed to power over 55,000 homes annually.

This power plan benefits locals too – Houston reports being able to maintain a relatively flat power price while increasing the amount of renewable energy in its mix, proving that going green doesn’t have to be costly.

Stockholm, Sweden

Sweden’s capital had already set an ambitious goal to be 100 per cent fossil fuel-free by 2050, but decided it should aim to achieve that target ten years sooner. Stockholm is making this task easier by first reducing the amount of overall energy it uses, then replacing fossil fuels with alternative sources such as biogas, biodiesel and solar. It doesn’t have far to go: fossil fuels currently make up just 9 per cent of its energy mix for power.

Sydney, Australia

Sydney proudly boasts one of the most ambitious emissions reduction targets in the country, and is hoping to achieve that in part through obtaining 30 per cent of its electricity from renewable sources by 2030. It also has the farthest to go compared to other cities on this list in this regard – its current energy mix is dominated entirely by coal.

The city’s renewable energy master plan draws on solar PV, solar thermal hot water, wind energy and geothermal from within the city’s boundary and other technologies (such as onshore wind turbines) to meet its goal.

Tokyo, Japan

One of the world’s largest mega-cities and among the first to earn that title, Tokyo has a big task in powering its 62 sprawling municipalities. The city is currently heavily reliant on fossil fuels, but officials are aiming to get a fifth of its total energy from renewable sources by 2024.

Part of its plan to achieve this is to establish a system in which consumers can chose clean energy – giving power, literally, to the people.

A couple of weeks ago, someone on Twitter asked CityMetric’s editor about the longest possible UK train journey where the stations are all in progressive alphabetical order. Various people made suggestions, but I was intrigued as to what that definitive answer was. Helpfully, National Rail provides a 3,717 page document containing every single timetable in the country, so I got reading!

(Well, actually I let my computer read the raw data in a file provided by ATOC, the Association of Train Operating Companies. Apparently this ‘requires a good level of computer skills’, so I guess I can put that on my CV now.)

Here’s what I learned:

1) The record for stops in progressive alphabetical order within a single journey is: 10

The winner is the weekday 7.42am Arriva Trains Wales service from Bridgend to Aberdare, which stops at the following stations in sequence:

The second longest sequence possible – 8 – overlaps with this. It’s the 22:46pm from Cardiff Central to Treherbert, although at present it’s only scheduled to run from 9-12 April, so you’d better book now to avoid the rush.

Not quite sure what you’ll actually be able to do when you get to Trehafod at half eleven. Maybe the Welsh Mining Experience at Rhondda Heritage Park could arrange a special late night event to celebrate.

There is a chance for a bit of CONTROVERSY with the last one, as you could argue that the final station is actually called London St Pancras. But St Pancras International the ATOC data calls it, so if you disagree you should ring them up and shout very loudly about it, I bet they love it when stuff like that happens.

Alphabetical train journeys not exciting enough for you?

2) The longest sequence of stations with alliterative names: 5

There are two ways to do this:

Ladywell, Lewisham, London Bridge, London Waterloo (East), London Charing Cross – a sequence which is the end/beginning of a couple of routes in South East London.

4) The greatest number of stations you can stop at without changing trains: 50

On a veeeeery slow service that calls at every stop between Crewe and Cardiff Central over the course of 6hr20. Faster, albeit less comprehensive, trains are available.

But if you’re looking for a really long journey, that’s got nothing on:

5) The longest journey you can take on a single National Rail service: 13 hours and 58 minutes.

A sleeper service that leaves Inverness at 7.17pm, and arrives at London Euston at 9.15am the next morning. Curiously, the ATOC data appears to claim that it stops at Wembley European Freight Operations Centre, though sadly the National Rail website makes no mention of this once in a lifetime opportunity.

6) The shortest journey you can take on a National Rail service without getting off en route: 2 minutes.

Starting at Wrexham Central, and taking you all the way to Wrexham General, this service is in place for a few days in the last week of March.

7) The shortest complete journey as the crow flies: 0 miles

Because the origin station is the same as the terminating station, i.e. the journey is on a loop.

8) The longest unbroken journey as the crow flies: 505 miles

Taking you all the way from Aberdeen to Penzance – although opportunities to make it have become rarer. The only direct service in the current timetable departs at 8.20am on Saturday 24 March. It stops at 46 stations and takes 13 hours 20 minutes. Thankfully, a trolley service is available.

9) The shortest station names on the network have just 3 letters

Ash, Ayr, Ely, Lee, Lye, Ore, Par, Rye, Wem, and Wye.

There’s also I.B.M., serving an industrial site formerly owned by the tech firm, but the ATOC data includes those full stops so it's not quite as short. Compute that, Deep Blue, you chess twat.

10) The longest station name has 33 letters excluding spaces

Okay, I cheated on this and Googled it – the ATOC data only has space for 26 characters. But for completeness’ sake: it’s Rhoose Cardiff International Airport, with 33 letters.

No, I’m not counting that other, more infamous Welsh one, because it’s listed in the database as Llanfairpwll, which is what it is actually called.

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